Biosphere

Q1. Give scientific reasons:1. Energy flow is unidirectional (or) At each trophic level from base to apex, the energy goes on decreasing in biomass pyramid. Ans. 1. In the biosphere the energy from the sun is trapped by the green plants. 2. The energy from the green plants in the form of food flows from one trophic level to the other trophic level. 3. AT every trophic level, a considerable amount of energy lost to the surrounding in the form of heat. 4. But this heat energy never returns to the sun. Therefore, energy flow is unidirectional. 2. At every trophic level there is decrease in biomass. Ans. 1. All the biomass produced by the green plants is not converted to biomass of the herbivorous. 2. As a rule, only 5% to 20% of the biomass at any trophic level can passed to the next one. 3. This is because a part of biomass is used for growth and maintenance at various trophic levels and a part is lost to the surrounding in the form of heat energy. 4. This shows that at every trophic level there is decrease in biomass. 3. The existence of life on the earth depends on the sun Ans. 1. Only the green plants (autotrophs) have the capacity to produce food with the help of solar energy during the process of photosynthesis. 2. Thus without solar energy food cannot be produced and without food organisms life cannot exist on the earth, therefore the existence of life on the earth depends on the sun. 4. Grasshopper is called first order consumer. Ans. Grasshopper is called first order consumer because 1. It is herbivore, which depends upon grass for its food. 2. Since it depends upon product directly, it is a primary consumer. Q2. Define 1. Biosphere:- The lithosphere, the atmosphere and the hydrosphere along with the life forms existing on the earth is called biosphere. 2. Autotrophs:-Self – feeding organisms are called autotrophs. Autotrophs consume the food prepared by them. For e.g. Green plants.

3. Heterotrophs:- Non – green plants, animals and most of the microbes which obtain their food either from green plants of from dead and decaying organic matter are called heterotrophs 4. Producers:- Green plants of the biosphere, which prepare food with the help of solar energy are called producers. 5. Consumers:- Animals, which consume green plants and some animals are called consumers. 6. Decomposers:- Microbes such as fungi, bacteria, protozoan which brings about the decomposition of dead bodies and their waste matter, are called decomposers. 7. Food chain :- Food chain is defined as transfer of food i.e. energy from one organisms to the other. 8. Food web:- Food web is defined as interconnections among different food chain at different trophic levels forming a network. 9. Trophic level:- Trophic level means feeding level. Each organisms of a food chain represents a trophic level. 10. Biomass:- Biomass is defined as increase in dry weight of organic matter of all organisms combined together at any trophic level. Q3. Distinguish between 1. Producers and Decomposers. Producers 1. Producers are autotrophs. 2. Producers use the food, which is produced by them. 3. Producers cannot bring about the decomposition of dead bodies and waster matter.

Decomposers 1. Decomposers are heterotrophs. 2. Decomposers use dead bodies of plant and animals as their food. 3. Decomposers bring about the decomposition of dead bodies and waste matter.

2. Consumers and Decomposers. Consumers 1. Consumers use the food produced by producers. 2. Consumers cannot bring about the decomposition of dead bodies and waster matter.

Decomposers 1. Decomposers use dead bodies of plant and animals as their food. 2. Decomposers bring about the decomposition of dead bodies and waste matter.

3. Abiotic component and Biotic component. Abiotic component 1. The abiotic component of the biosphere includes factors like light, humidity, temperature, soil, minerals,

Biotic component 1. The biotic component of the biosphere are plants, animals and micro – organisms.

water and atmospheric pressure. 2. The abiotic components are non living components.

2. The biotic components are living components.

4. Autotrophs and Heterotrophs. Autotrophs 1. Self feeding plants are called autotrophs. 2. Autotrophs are green in colour due to the presence of chlorophyll.

Heterotrophs 1. Plants, animals which obtain their food either from autotrophs or from dead and decaying organic matter are called heterotrophs. 2. Heterotrophs are non green colour due to the absence of chlorophyll.

5. Producers and Consumers Producers 1. Producers are autotrophs. 2. Producers use the food, which is produced by them. 3. All green plants of the biosphere are producers.

Consumers 1. Consumers are heterotrophs. 2. Consumers use food produced by the producers. 3. All animals of the biosphere are consumers.

6. Photosynthesis and Respiration. Photosynthesis 1. Photosynthesis is a constructive process in which glucose is synthesized from CO2 and H2O. 2. Photosynthesis is a light dependent process. 3. In this, energy is stored in organic compounds

Respiration 1. Respiration is a destructive process in which glucose is broken down into CO2 and H2O. 2. Respiration is independent of light. 3. In this, energy is released from organic compounds.

Q4. Answer the following:1. In which of the following food chain man get more energy? Why? i. Maize --------- Man ii. Maize ------ Goat ------ Man Ans. Man gets more energy from the first food chain. This is because, shorter the food chain, lesser is loss of energy. The second food chain being larger, there is more loss of energy. 2. In the following example which is a part of the food chain: Frog ------ Snake ----- Hawk , if the snake population declines, what will happen to 1. Population of frog, 2. Population of Hawk.

Ans. The population of frog will increase and population of hawk will decrease. This is because snake consume frog and hawk consume snake. 3. What is a food web? Describe the important aspects of food web. Ans. Food web is defined as interconnections among different food chains at different trophic level forming a network. Important aspects of food web are: 1. It starts from an autotroph i.e. Producer. i.e. Producer. 2. It has many connecting food chains. 3. The number of links in the chain are variable. Decomposers can operate at any level. They are dead plant materials, dead bodies of herbivores and carnivores as the source of energy. 4. Name the tropic level represented by the larvae of mosquitoes in the food chain from a pond. Give reason. Ans. 1. The larvae of mosquitoes represent primary consumers in the food chain from a pond. 2. This is because, they feed on algae of the pond, which trap the solar energy and make it available to the larvae of mosquitoes. 5. What is photosynthesis? State its importance. Ans. The process by which green plants synthesize carbohydrate from carbon dioxide and water in the presence of sunlight is called photosynthesis. Importance of photosynthesis. a. The green plants absorb the solar energy during photosynthesis and convert this radiant energy into chemical energy. b. The energy required for different life activities comes from oxidation of sugars produced during photosynthesis. 6. What will happen if all the number of frogs becomes less in nature? Ans. 1. If the number of frogs becomes less the number of grasshoppers will increase with corresponding decrease in the number of snakes. 2. This is because frogs consume grasshoppers, while snake consume frogs. 7. What will happen if all the green plants disappear from the earth? Ans. 1. If all the green plants disappear from the earth there will be no food preparation by the process of photosynthesis. 2. In absence of photosynthesis neither the food nor the oxygen will be available to other living organisms. 3. In absence of good and oxygen, life will not exist on the earth. 8. What is the role of producers in the biosphere? Ans. The producers play the following roles in the biosphere:

1. The producers provide food to different organisms of the biosphere. 2. The producers provide energy to the different organisms of the biosphere. 9. The graph of biomass is called energy pyramid. Ans. 1. When plotted on the graph paper, the biomass at various trophic levels forms a pyramid. 2. As the biomass contains energy in the form of organic molecules. Hence, the graph of biomass is called energy pyramid. Q5. Draw the following graphic representation: 1. The food web involving at least three food chains. 2. A food web with the help of following organism, grass, shrub, deer, sheep, rabbit, wolf, lion man. 3. The food chain is aquatic surroundings. 4. Draw a neat labeled diagram of energy flow. 5. Give the schematic representation of different trophic level.